/*
 * CenteredScaleOperator.java
 *
 * Copyright (C) 2002-2006 Alexei Drummond and Andrew Rambaut
 *
 * This file is part of BEAST.
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership and licensing.
 *
 * BEAST is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 *  BEAST is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with BEAST; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
 * Boston, MA  02110-1301  USA
 */

package dr.inference.operators;

import dr.inference.model.Parameter;
import dr.math.MathUtils;
import dr.xml.*;

/**
 * A generic operator for use with a sum-constrained vector parameter.
 *
 * @author Alexei Drummond
 * @author Andrew Rambaut
 *
 * @version $Id: CenteredScaleOperator.java,v 1.20 2005/06/14 10:40:34 rambaut Exp $
 */
public class CenteredScaleOperator extends SimpleMCMCOperator implements CoercableMCMCOperator {
	
	public static final String CENTERED_SCALE = "centeredScale";
	public static final String SCALE_FACTOR = "scaleFactor";
	
	public CenteredScaleOperator(Parameter parameter) {
		this.parameter = parameter;
	}
	
	public CenteredScaleOperator(Parameter parameter, double scale, int weight, int mode) {
		this.parameter = parameter;
		this.scaleFactor = scale;
		this.weight = weight;
		this.mode = mode;
	}
	
	/** @return the parameter this operator acts on. */
	public Parameter getParameter() { return parameter; }

	/** 
	 * Change the parameter and return the hastings ratio. 
	 * Performs a centered scale operation on the vector
	 * and returns the hastings ratio.
	 * This operator changes the variance but maintains the order
	 * of the scalars.
	 */
	public final double doOperation() throws OperatorFailedException {
		
		double total = 0.0;
		
		for (int i = 0; i < parameter.getDimension(); i++) {
			total += parameter.getParameterValue(i);	
		}
		double mean = total / parameter.getDimension();
		double scaleFactor = getRandomScaleFactor();
		double logq = parameter.getDimension() * Math.log(1.0 / scaleFactor);
	
		for (int i = 0; i < parameter.getDimension(); i++) {
			
			double newScalar = (parameter.getParameterValue(i) - mean) * scaleFactor + mean;
			if (newScalar < parameter.getBounds().getLowerLimit(i) || newScalar > parameter.getBounds().getUpperLimit(i)) {
				throw new OperatorFailedException("Proposed value out of bounds");
			}
			parameter.setParameterValue(i, newScalar);
		}
		
		// non-symmetrical move
		return logq;
	}
	
	public final double getRandomScaleFactor() {
		return scaleFactor + (MathUtils.nextDouble() * ((1/scaleFactor) - scaleFactor));
	}

	// Interface MCMCOperator
	public final String getOperatorName() { return parameter.getParameterName(); }

	public double getCoercableParameter() {
		return Math.log(1.0/scaleFactor - 1.0);
	}
	
	public void setCoercableParameter(double value) {
		scaleFactor = 1.0/(Math.exp(value) + 1.0);
	}
	
	public double getRawParameter() {
		return scaleFactor;
	}
	
	public int getMode() { 
		return mode; 
	}

	public double getTargetAcceptanceProbability() { return 0.234;}
	public double getMinimumAcceptanceLevel() { return 0.1;}
	public double getMaximumAcceptanceLevel() { return 0.4;}
	public double getMinimumGoodAcceptanceLevel() { return 0.20; }
	public double getMaximumGoodAcceptanceLevel() { return 0.30; }
	
	public final String getPerformanceSuggestion() {
        
		double prob = MCMCOperator.Utils.getAcceptanceProbability(this);
		double targetProb = getTargetAcceptanceProbability();
		dr.util.NumberFormatter formatter = new dr.util.NumberFormatter(5);
		double sf = OperatorUtils.optimizeScaleFactor(scaleFactor, prob, targetProb);
		if (prob < getMinimumGoodAcceptanceLevel()) {
			return "Try setting scaleFactor to about " + formatter.format(sf);
		} else if (prob > getMaximumGoodAcceptanceLevel()) {
			return "Try setting scaleFactor to about " + formatter.format(sf);
		} else return "";
	}
	
	public int getWeight() { return weight; }

	public void setWeight(int w) { weight = w; }
	
	public static XMLObjectParser PARSER = new AbstractXMLObjectParser() {
		
		public String getParserName() { return CENTERED_SCALE; }
		
		public Object parseXMLObject(XMLObject xo) throws XMLParseException {
		
			Parameter parameter = (Parameter)xo.getChild(Parameter.class);
			
			int mode = CoercableMCMCOperator.DEFAULT;
			if (xo.hasAttribute(AUTO_OPTIMIZE)) {
				if (xo.getBooleanAttribute(AUTO_OPTIMIZE)) {
					mode = CoercableMCMCOperator.COERCION_ON;
				} else {
					mode = CoercableMCMCOperator.COERCION_OFF;
				}
			}
			
			double scale = xo.getDoubleAttribute(SCALE_FACTOR);
			int weight = xo.getIntegerAttribute(WEIGHT);
			CenteredScaleOperator op = new CenteredScaleOperator(parameter);
			op.setWeight(weight);
			op.scaleFactor = scale;
			op.mode = mode;
			return op;
		}
		
		public String getParserDescription() {
			return "A centered-scale operator. This operator scales the the values of a multi-dimensional parameter so as to perserve the mean. It does this by expanding or conrtacting the parameter values around the mean.";
		}

		public Class getReturnType() { return CenteredScaleOperator.class; }

		public XMLSyntaxRule[] getSyntaxRules() { return rules; }
	
		private XMLSyntaxRule[] rules = new XMLSyntaxRule[] {
			AttributeRule.newIntegerRule(WEIGHT),
			AttributeRule.newDoubleRule(SCALE_FACTOR),
			AttributeRule.newBooleanRule(AUTO_OPTIMIZE, true),
			new ElementRule(Parameter.class)
		};
	};

	public String toString() { return getOperatorName() + "(scaleFactor=" + scaleFactor + ")"; }
	
	// Private instance variables
	
	private Parameter parameter = null;
	private double scaleFactor = 0.5;
	private int mode = CoercableMCMCOperator.DEFAULT;
	private int weight = 1;
}
